In the winter trees and shrubs can suffer from desiccation. This is when plants are in the state of extreme dryness, or when plants are in the process of extreme drying. Damaged foliage which looks burned can appear on trees. There are several reasons why this can occur. Often it is from trees becoming dried out from wind or ice melting. It can also be the case where premature pruning hastened this condition. Ice-melting chemicals applied to get rid of ice nearby can cause it. (That’s why you often see the road-facing side of pines along the highway having turned brown.) The wind and the lack of moisture in the air or in the soil are other reasons. Another is the age-old problem: the wrong plant planted in the wrong location.
Evergreens are always losing moisture; even in the winter their leaves are always losing water. It’s an exchange when the leaves lose more water than the roots are taking in, and burned out foliage occurs. The leaves or needles appear dry and brown or rust-colored. At the first really cold weather, the root system freezes so there is either a decrease in water or no water at all for the roots. Then when the weather turns very sunny and warm while the ground is frozen, the evaporation of water occurs and the discolored foliage starts to appear. The sides of the tree exposed to the wind often suffer the worst damage.
If your evergreens are showing winter burn, on a warm day hook up the hose and water the area around the tree and water the frozen ground so the tree can take in moisture. Don’t do it on a really cold day or the hose will freeze and burst. Be sure to disconnect the hose and remove it when you are done. As the weather warms, trim off the burned areas and apply a root feeder appropriate for evergreens. It’s important to remove the damaged sections as they can attract insects and disease.
Next fall, add two to three inches of mulch around the trees to help maintain moisture. Water thoroughly before the ground freezes, and add windbreaks or wrap with burlap to minimize moisture loss from wind.
If your evergreens suffer winter burn year after year despite your attempts to prevent it, perhaps you may consider replacing your trees and shrubs with more winter hardy varieties such as Sitka and Colorado blue spruces and hollies. If you have questions about appropriate evergreen trees and shrubs for the Minneapolis area, give us a call.